Hello Gerry-san Thank you very much for your reply. I understood that the error I saw is something expected and the measuring way with multiple thermo-couplers electrically shorted is allowed as long as those common mode is within +/-7.5V. Thank you very much again for your support. Regards Kazu :D

Hello support, When I used multiple channels to measure temperature on same conductive surface, those showed some differences in tempareture. Then, I tried to solder a tip of multiple K-types on same electrically conductive metal to ensure no contact issue. But I still see several degree difference ...